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Author Topic:   Falsifying a young Universe. (re: Supernova 1987A)
Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 61 of 948 (176291)
01-12-2005 3:58 PM
Reply to: Message 60 by Percy
01-12-2005 3:14 PM


Re: a simple question
As far as absolute distances in space go, there's at least one that's purely trigonometrically determined at 25,000,000 light years, plus or minus a million. It's to a galaxy called Messier ( pronounced mess-ee-AY, after a French astronomer) 106. The galaxy's nucleus has a ring of gas orbiting it, and we can tell how fast it's turning from the Doppler effect - its light is redshifted on one side and blueshifted on the other. Also, "knots" of radio emission in the ring are moving across our line of sight, and their angular motion was measured over a few years with terrifically accurate radiotelescopes. The combination of angular distance and speed immediately gives distanc traveled by the knots, and thus distance to them by triangulation.
I have the paper at home - link tonight when I get there.

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Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 71 of 948 (176382)
01-12-2005 9:40 PM
Reply to: Message 61 by Coragyps
01-12-2005 3:58 PM


Re: a simple question
Reference for the galaxy distance above is Herrnstein, et al., Nature, v 400, pp 539-541, (1999). And, like most professional astronomers talking of distance, they never say "light year." The parsec is the real unit of distance in astronomy - 7.2 megaparsecs in this case.

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Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


(1)
Message 123 of 948 (177061)
01-14-2005 5:02 PM
Reply to: Message 122 by simple
01-14-2005 4:38 PM


Re: who turned out the lights?
The Greek gods were based also, to some extent on real spirits.
Off topic, I know, but I spewed coffee all over the screen at this one. Wow!

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Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 236 of 948 (179772)
01-22-2005 7:44 PM
Reply to: Message 228 by RAZD
01-22-2005 4:55 PM


Re: The Math of the Matter?
how fast is the gas moving away from the original star and then how far has it gotten in the (now 2005-1987=) 18 years since?
In case you're not clear on this - the gas in the ring was ejected long before the supernova blew, and at velocities of maybe a couple of hundred km/sec - negligible compared to the speed of light. My guess would be that the actual motion of the gas making up the rings would be so slight as to be undetectable at that distance - unless we might be able to see Doppler effects at the near and far edges. The progressive illumination of different parts of the rings is what we saw.

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Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 248 of 948 (179883)
01-23-2005 9:22 AM
Reply to: Message 247 by RAZD
01-23-2005 8:49 AM


Re: distance by the 'regular' method for {Sanduleak -69202}}
The supernova was in the Large Magellanic Cloud, which is in orbit around the Milky Way. The cosmological red shift that you're thinking of doesn't apply here - only to much further-off galaxies that aren't gravitationally bound to us. I've read, long ago, of distances to the LMC based on Cepheid variables, a type of star whose period of variation correlates with brightness. Distance using these was similar to that from 1987A, but as I remember it, there's uncertainty in the Cepheid yardstick arising from the slightly different chemical composition of the LMC relative to our neighborhood.
Added in edit:
http://arxiv.org/PS_cache/astro-ph/pdf/9805/9805215.pdf
gives a comparison of a couple of methods with SN1987A, but the results are stated in terms of "distance modulus", something expressed as a brightness. We'll need a real astronomer to help here.....
But the distance moduli are all within each others' error bars, anyway.
Added in another edit:
http://arxiv.org/PS_cache/astro-ph/pdf/0010/0010590.pdf
gives several methods, and has all distances coming out within 7% of each other.
This message has been edited by Coragyps, 01-23-2005 09:33 AM
This message has been edited by Coragyps, 01-23-2005 09:38 AM

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Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 253 of 948 (179936)
01-23-2005 1:10 PM
Reply to: Message 251 by RAZD
01-23-2005 12:01 PM


Re: distance by the 'regular' method?
If this system is used to calibrate red shift then there must be red shift information on it, or at least I would think so.
Alas, it's not that easy....
I'm sure there are plenty of red shifts measured for objects in the LMC, but they have nothing to offer as far as distance to the LMC. It's in orbit around us and not receding due to cosmological expansion.
Conversely, though, there is a lot of data on Cepheid and RR Lyrae variables in the LMC that can be compared with data on those same two types of stars in galaxies that are far enough away to exhibit cosmological redshifts - say, in the Virgo Cluster. The links I gave above allude to this, but they are preaching to the choir of astronomers who already know all the basics of such measurement - we need a more popularised treatment here. Whatever the case, my 2nd link claims 7% spread in distances derived from SN1987A and the variable-star methods. That sounds pretty good to me....

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Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 264 of 948 (180619)
01-25-2005 9:51 PM
Reply to: Message 263 by daaaaaBEAR
01-25-2005 9:11 PM


Re: logic
Hello, Minnesotan Bear!
Is their proof for the Big Bang? and if so how does this agree with the idea that all explosions are destructive not constructive.
That's not strictly on topic for this thread, but there are other threads near at hand here that deal with these questions. Briefly: yes, there's heaps of evidence (not "proof"). The Big Bang was not an explosion but more of a seriously large "unfolding."
Poke around this one forum a while, and you'll find some very detailed discussions.....

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Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 266 of 948 (180627)
01-25-2005 10:21 PM
Reply to: Message 265 by daaaaaBEAR
01-25-2005 10:10 PM


Re: logic
"Big Bang - Big Dud" is open and closer to your topic. The admins and mods around here try hard to keep threads focussed - it really does make for more productive discussions.
The Bang preceded any matter at all - only energy was there. We don't have a word, or even a good non-mathematical concept - of what it was like, because nothing analogous to it is anywhere in our experience. Calvin (of Calvin and Hobbes) liked "The Humungous Space Kerblooey!!!!" - and why not?

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Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 277 of 948 (195062)
03-28-2005 9:59 PM


A slight veer to the edge of this topic:
A. Brunthaler, et al., Science, v307, pp1440-1443 (2005 Mar 4)
"The Geometric Distance and Proper Motion of the Triangulum Galaxy (M33)" - the abstract:
We measured the angular rotation and proper motion of the Triangulum Galaxy (M33) with the Very Long Baseline Array by observing two H2O masers on opposite sides of the galaxy. By comparing the angular rotation rate with the inclination and rotation speed, we obtained a distance of 730 168 kiloparsecs. This distance is consistent with the most recent Cepheid distance measurement. M33 is moving with a velocity of 190 59 kilometers per second relative to the Milky Way. These measurements promise a method to determine dynamical models for the Local Group and the mass and dark-matter halos of M31, M33, and the Milky Way.
730 kiloparsecs = 2.4 million light years. That's by direct measurement and trigonometry.
PH, if SN1987A is 4144 light years away, why are the stars in the LMC so very, very dim?

  
Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


(1)
Message 672 of 948 (826990)
01-15-2018 1:37 PM
Reply to: Message 670 by creation
01-15-2018 1:21 PM


Re: The Win-Win situation for Science
The only time that enters into parallax measurement is the time it takes for the earth to travel halfway around the sun. Will you agree that six months on Earth is about, oh, six months in duration? And that the time doesn’t matter anyway, only the distance?

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Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


(2)
Message 802 of 948 (841532)
10-14-2018 3:53 PM
Reply to: Message 801 by creation
10-14-2018 3:38 PM


Re: Voyager 1 enters new space
Yeah, you might want to stay away from Tyre, at least.

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Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 927 of 948 (844303)
11-27-2018 8:40 PM
Reply to: Message 924 by creation
11-27-2018 5:03 PM


Re: Confusing
You are mistaken again/still. Time has crap-all to do with measuring parallax, except that it takes six months for our earth to go half an orbit. And you, creation, have said that orbit is inside our bubble . Parallax is just 11th grade trigonometry.

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Coragyps
Member (Idle past 725 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 935 of 948 (844377)
11-28-2018 10:11 PM
Reply to: Message 931 by creation
11-28-2018 6:50 PM


Re: Confusing
Was post 931 intended to have any meaning, or to respond to anything I wrote?

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